1. Field of the Invention
The invention relates generally to switching amplifiers, and more specifically, to error correction in switching amplifiers.
2. Background of the Invention
Digital audio switching power amplifiers are well known and widely used, for example, in the automotive audio industry. In such amplifiers, a digital audio signal which has been pulse width modulated is applied to a switching power amplifier which drives a load, typically a speaker, to reproduce an audio signal represented by the pulse width modulated signal.
The audio fidelity of such high efficiency switching amplifiers is typically determined by the non-idealities of the switching power stage. Additionally, digital audio switching power amplifiers that do not incorporate feedback suffer from poor power supply rejection. Prior attempts to improve fidelity and power supply rejection in light of these non-idealities have proposed incorporating a feedback mechanism to digitally correct the distortion introduced by these non-idealities. However, the existing digital correction limits the input signal dynamic range, thus reducing the maximum power produced by the switching amplifier. In addition, with such existing digital correction, if the power stage delay becomes too large, then the feedback system may become difficult to stabilize.